WEANING OF PIGS RAISED IN SOW-CONTROLLED AND IN CONVENTIONAL HOUSING SYSTEMS .1. DESCRIPTION OF SYSTEMS, PRODUCTION, AND BACTERIOLOGY

An alternative weaning system (sow-controlled, SC) where the sow could leave the lactation pen for a common sow pen, but the pigs could not, was studied and compared to a conventional system (CONV) where each p en housed a sow and her litter. The trial period began one week after farrowing when each system received 4 sows and litters, and stopped 4 weeks after weaning. Pigs had access to creep feed and were weaned at 5 weeks of age. Twenty-two SC and 23 CONV litters were studied. Before weaning, the SC pigs had a significantly poorer daily gain and higher consumption of creep feed. After weaning, no significant differences in daily gain or feed consumption were found, but the SC pigs tended t o have a poorer feed conversion. The blood plasma levels of immunoreac tive cationic trypsin (IRCT), an indicator of pancreas function and de velopment, began to increase at 3 weeks of age, and continued to rise during the trial period. The CONV pigs had a greater increase during t he suckling period, in spite of eating less creep feed. Some SC pigs s howed a dominance of haemolytic E. coli in rectal swabs at weaning, in dicating that weaning may already have begun. A high proportion of hae molytic E. coli did not always induce post-weaning diarrhoea (PWD). In general, the incidence of PWD was low. The stockpersons considered th e SC system to be more difficult to manage because of the larger area to be cleaned and because the pigs occasionally managed to get out of their pens.